Posture chair



Feb.9,1943. EBHA'RMAN' 2,310,366` l `PosTURE CHAIR Filed qune 24, 1959 2 sheets-sheet 1 Feb. 9, F B HARMAN 2,310,366

POSTURE CHAIR i Filed June 24, 1939' 2 sheets-sheet 2 n ,Zf .4 Zay y Patented Feb. 9, 1943 'reir or 4 Claims.

This invention relates generally to posture chairs and specifically to a type of posture chair in which the back and seat are relatively adjustable.

It is the Ipurpose of posture chairs of the type described to provide adequate and proper support for the back and legs of a person seated in the chair. Such support is only adequate andproper when the seat of a chair is of such a length as to offer support for the entire upper part of the legs and when the height of the back of the chair is sufficient to support the person in the chair at the pro-per point along the spine. It is known that a tall person requires a greater back height and a greater seat length than does a short person, for the reason that a tall person generally has a longer body trunk and correspondingly longer upper leg portions. Furthermore, I have found that the ratio of the difference in back height required for any two normal people of diierent height to the difference in seat length required for the same two people is substantially constant.

It is the principal object of this invention to provide a posture chair of the type described wherein the back height and seat length of the chair may be simultaneously increased or decreased. It is another object of this invention to provide a posture chair of the type described wherein the ratio of the increment of change in the back height to the increment of change in the seat length is substantially constant.

It is still another object of this invention to provide a posture chair of the type described wherein the back height and seat length of the chair may be simultaneously increased or decreased by a single manual control operable by a person seated in the chair.

It is a further object of this invention to provide means adaptable to posture chairs of the type described fullling all of the above-named objects.

Other objects and advantages will be understood from the following description of the two possible embodiments of my invention.

In the drawings- Figure 1 is a fragmentary elevation, partly in section, of an embodiment of a posture chair of my invention showing in detail means for eecting movement of the back and seat of the chair;

Figure 2 is a section taken on the line 2-2 of Figure 1;

Figure 3 is a section taken on the line 3-3 of Figure 1;

Figure 4 is a section taken on the line 4-4 of Figure 1;

Figure 5 is a detail, partly in section, showing a modication of the means illustrated in Figure 1; and

Figure 6 is a fragmentary section taken on the line 6--6 of Figure 5.

The posture chair illustrated in Figure 1 has a seat I0, a back I I and a base I2. The seat and the back are supported by adjusting means which includes a head or frame I3 supported above the base I2 by a threaded spindle I4. The spindle extends downward from the head I3 and is slidably journaled in the base I2. I'he spindle is maintained at a desired level in the base by a plate-nut I5 supported on the base and threadedly engaging the spindle.

The chair described may be modied in many known ways. For example, the head I3 may be supported on a xed base rather than the swivel type described, or the adjusting means may be only connected to the back and seat; the chair may have arms and a foot rest; the seating portions of the chair may be upholstered or plain, and many other such modifications may be made.

In one embodiment of the chair, the adjusting means comprises the head or frame I3 which consists of an elongated substantially U-shaped member (see Fig. 4) having a yoke portion I8, side limbs I9, and a horizontally extending channel member 2li. The channel member is secured through its anges 2I `and 22 to the head I3 by krivets 23 or other suitable means at a point sufficiently distant from the ends of the side limbs I9 to provide stubs 24 and 25. Slidably mounted on the stubs 24 and 25 is a sled-like bracket 26 which carries the seat IB.

The sled-like bracket 26 consists of oppositely disposed angle members 21 and 28 having One edge slidably engaging the top and the other edge engaging the outside surfacey of the studs 24 and 25 respectively. At each of the ends of the angle members 21 and 28 offset in an upwardly direction are apertured feet 29 to which is fixed the seat I0 by screws 30 or other suitable means.

In order to prevent the bracket 25 from disengaging the studs 24 and 25, a channel plate 32 is placed around the angle members, and its flanges are secured to the side limbs I9 by the rivets 23 or other means. The plate 32 slidably engages the outside surfaces of the angles 21 and 28 and thus insures the stability of the seat I0 relative to the head I3.

Rigidly secured to the head I3 at the outer end ofthe channel member 20 by suitable means is a substantially vertical guide plate 33. This plate has parallel vertical edges 34 and 35 which are correspondingly angularly disposed to the central portion of the plate.

Slidably engaging the edges 34 and 35 of the guide plate 33 is an arcuate yoke 36 to the ends of which are secured parallel bars 31 for supporting the back At the middle portion of the yoke are a pair of oppositely disposed, oblique angle irons 38 each having one of its limbs 39 fixed to the yoke 36 by rivets 39a and the other of their limbs 40 slidably engaging the outer surface of the vertical edges 34 and 35 of the guide plate 33 (see Fig. 3).

Rotatably mounted on the guide plate 33 and on the channel member 20 of the frame are screw shafts 4| and 42 having threaded portions 43 and 44 respectively. The screw shaft 4| is.

journaled through an apertured lug 45 which is secured to the central portion of the channel member 29 by rivets 46 and threadedly engages a nut 41 secured to a cross angle bar 48 which connects the two angle members 21 and 28 of the bracket 26. The screw shaft 42 is journaled through a pair of apertured lugs 49 which are secured at the top and bottom of the central portion of the guide plate 33 by screws 50 and threadedly engages, intermediate the lugs, a nut which is secured to the central portion of the yoke 36 by screws 52. The screw shafts are rotatably connected by bevel gears 53 and 54. The gear 53 fits over the right hand end of the screw shaft 4| and is xed thereto by a pin passing through the sides of the gear collar and the shaft 4|, as shown. The bevel gear 54 is xed to the screw shaft 42 and is positioned so as to mesh with the gear 53. Stop collars 55 and 56 are xed on screw shafts 4| and 42, respectively, for preventing longitudinal movement of the shafts with respect to their supporting members.

From the above description of the adjusting means, it is seen that a rotation of either screw shaft-4| or screw'shaft 42 by suitable means will effect simultaneously a linear movement of the bracket 26 carrying the seat I6 along the studs 24 and 25 of the head I3 and a movement of the yoke 31 carrying the back along the edges 34 and 35 of the guide plate 33.

As an illustration of one such means, there is provided a bevel gear 58 which is xed to the screw shaft 4| and which is meshed with a second bevel gear 59. The gear 59 is fixed to the end of a rotatable rod 69.

The rod 6E! is journaled in a hub-like bearing 6| which is formed in one of the side limbs I9 of the head I3. A suitable hole 62 is cut in the flange 22 of the channel 20 to allow for the bearing. There is also a suitable hole 63 in the channel 32 to permit the rod 66 to pass freely therethrough. The rod is prevented from longitudinal movement in the bearing by stop collars 64 and 65. Fixed to the outer end of the rod 69 is a handle 66 by which the entire adjusting mechanism may be operated by a person seated in the chair.

It will readily be seen that a rotation of the handle 66 in one direction will, through the cooperation of the bevel gears 58 and 59, produce a corresponding rotation of the screw shafts. This rotation of the screw shafts will produce a linear movement of the seat and the back since these threadingly engage the screw shafts in the above described manner. It is therefore only necessary to provide the screw shafts with threads that will cause simultaneously an upward movement of the back and an outward movement of the seat, and. then, if the handle 66 is rotated in the opposite direction, there will be simultaneously a downward movement of the back and an inward movement of the seat. In Figure 1 the position of the seat and the back when the chair has the greatest seat length and back height is indicated by the broken line illustration of the seat and back, and their supporting brackets.

When it is desired to lock the adjusting means in order to prevent the position of the seat and back from being altered, there is provided locking means in cooperation with the guide plate 33 and the yoke 36. The locking means comprises a handle 61 having a threaded stem 68 which engages an extension 69 of the limb 39 of one of the angle irons 38 which are secured to the yoke 36. The end of the stem 66 abuts the yoke 36 so that by turning the handle 61 in one direction the extension 69 moves away from the yoke, causing part 33 to rotate about the rivet 39a, which may be suihciently loose for this purpose, and the limb 40 is thus pressed tightly against the edge 34 of the guide plate 33. This increased pressure between parts 46 and 34 creates suicient friction to prevent any movement of the mechanism by a rotation of the handle 66.

Another embodiment of a chair of this invention may have an adjusting means of the construction illustrated in Figures 5 and 6. Figure 5 is a section similar to that of Figure 1 for the previously described embodiment.

Said adjusting means is carried by a generally U-shaped head or frame 'I0 having partially offset side limbs 1| that flare at their ends and a yoke portion 'l2 from which extends a spindle l5 similar to the previously described embodiment. Fixed by rivets 13 to the ends of the side limbs are a pair of angle irons 14 having feet 15 to which is attached the seat in the manner previously described. Said rivets '13 also serve to secure a channel member 'I6 to the ends of the side limbs 1I to form a part of the head '16.

On the rear end of the channel 16, there is fixed by rivets 'Vl a guide plate which, because of its substantially identical construction to the guide plate described above, is numbered 33', having the angular edges 34' and 35. The plate 33 is secured to the channel 16 preferably at an angle of approximately forty-five degrees (45) With the horizontal.

The guide plate 33 slidably supports the back in the same manner as in the above described embodiment, and the parts are so numbered that reference may be made to the previous description. It is to be noted, however, that the bars 31 which carry the back are joined with the yoke 36' in a manner which permits the back to assume a vertical position.

In order to rotate the screw shaft 44', there is provided gearing consisting of a miter gear 'IB xed to the lower end of the screw shaft and a miter pinion 19 meshed with the miter gear and xed on the end of a rod 89.

The rod 8U is journaled in bearings 8| and 82 which may be integral with the head I6 or mounted thereon. The rod preferably extends forward and upward so that a handle 83 which is xed to the outer end may be readily accessible to a person seated in the chair. The rod 8D and screw shaft 44' are prevented from relative longitudinal movement by the action of the stop collars 34 and 85 and their respective gears.

It will be seen that a rotation of the handle 83 by a person seated in the chair will cause a rotation of the screw shaft 44 and thus a linear movement of the yoke 36'. As the yoke moves upward along the guide plate 33', the back of the chair will be moving simultaneously upward and outward, and, as the yoke moves downwardly along the guide plate, there is a simultaneous downward and inward movement of the seat. rlhe uppermost position is shown by the broken line in Fig. 5. These changes in the position of the back of the chair relative to the seat. effect simultaneously an increase in the back height and the seat length and simultaneously a decrease in the back height and the seat length.

This latter embodiment may .also be provided with a locking means substantially similar to that described above. Such a means is illustrated in Figure 6, and the reference numbers correspond to the above description except that the stem 68 threadingly engages the yoke 36 and abuts the extended portion of the limb 68.

It will be seen that, if the screw shaft 44 and its associated parts become broken or damaged, they may be removed without destroying the usefulness of the adjusting means, since the proper adjustment of back height and seat length may be made by sliding the back along the guide plate and then, when the desired position is obtained, the handle 61 may be turned in order to lock the back in that position.

Other embodiments of this invention may be constructed by those skilled in the art without deviating from the spirit of this invention. Such modifications are intended to come within the scope of the following claims to an extent commensurate with the art.

I claim:

l. A posture chair of the type described, comprising a seat, a back, and means supporting said seat and said back, said means comprising a frame, a pair of screw shafts rotatably mounted on said frame, one of said shafts threadedly engaging said back, and the other of said shafts threadedly engaging said seat, gearing for rotatably connecting said screw shafts, and means for rotating one of said screw shafts, said screw shafts being so related that the rotation of one effects simultaneously an upward movement of the back and an outward movement of the seat and simultaneously a downward movement of the back and an inward movement of the seat.

2. A posture chair of the type described, comprising a seat, a back, and means supporting said seat and said back, said means comprising a frame, a sled-like bracket carrying said seat slidable horizontally on said frame, a substantially vertical guide plate secured to said frame, a yoke carrying said back in a substantially vertical position slidably engaging said guide plate, a screw shaft rotatably mounted on said frame and threadedly engaging said sled-like bracket, a second screw shaft rotatably mounted on said guide plate and threadedly engaging said yoke, gearing for rotatably connecting said screw shafts, and means for rotating one of said screw shafts, said screw shafts being so threaded that the rotation of one effects simultaneously an upward movement of said back and an outward movement of said seat and effects simultaneously a downward movement of said back and an inward movement of said seat.

3. A posture chair substantially as described in claim l, wherein the means for rotating one of said screw shafts includes a rod journaled in said frame, gearing for rotatably connecting said rod and one of said screw shafts, and a handle fixed on said rod, said handle being accessible to a person seated in the chair for manually rotating said rod and thus said screw shaft.

4. In a posture chair of the class described having a seat and a back, a frame, a pair of screw shafts rotatably mounted on said frame, one of said screw shafts being horizontally dis posed and threadedly engaging the seat and the other screw shaft being vertically disposed and threadedly engaging the back, gearing for rotatably connecting said screw shafts, and means for rotating one of said screw shafts so as to effect a simultaneous horizontal movement of `the seat and a vertical movement of the back.

FRANK B. HARMAN. 

